1. Field of Invention
The present invention relates to an implantable prosthesis for positioning and supporting a breast implant within a patient and a method of positioning and supporting the breast implant within the patient using the implantable prosthesis.
2. Description of Related Art
The American Society of Plastic Surgeons reports that breast augmentation procedures increased seven-fold in the ten-year period between 1992 and 2002, increasing from 32,607 procedures in 1992 to 225,818 procedures in 2002. Overall it has been estimated from breast implant sales data that anywhere between 1.5 to more than 2 million women in the United States alone have breast implants. An estimated 70-80% of breast augmentation procedures were performed for cosmetic purposes while the remaining 20-30% were performed for reconstructive purposes.
Implants are positioned within the chest in one of three positions: (1) implant over the pectoralis major muscle and under the breast tissue (subglandular); (2) implant partially under the muscle (partial submuscular); and (3) implant completely under the muscle (submuscular). The subglandular placement puts the implant directly behind the breast tissue and mammary gland and in front of the pectoralis major muscle. This placement requires the least complicated surgery and yields the quickest recovery. The downsides of this placement are increased chances for capsular contracture, greater visibility and vulnerability for the implant. This is because only the skin and breast tissue separate the implant from the outside world. Depending on the amount of available breast tissue the implant may be seen “rippling” through the skin.
Partial submuscular placement involves placing the implant under the pectoralis major muscle. Because of the structure of this muscle, the implant is only partially covered. This alternative reduces the risk of capsular contracture and visible implant rippling, but recovery time from this positioning is typically longer and more painful because the surgeon has to manipulate the muscle during surgery. Also, because of increased swelling, the implant may take longer to drop into a natural position after surgery. Completely submuscular placements puts the implant firmly behind the chest muscle wall. The implant is placed behind the pectoralis major muscle and behind all of the supporting fascia (connective tissue) and non-pectoral muscle groups. This placement has even longer recovery time, potential loss of inferior pole fullness, and involves a more traumatic surgical procedure.
Regardless of location of the implant, in the case of breast augmentation the surgery is carried out through an incision placed to minimize long-term scarring. The incision is made in one of three areas: (1) peri-areolar incision; (2) inframammary fold incision; and (3) transaxillary incision. The peri-areolar incision enables the surgeon to place the implant in the subglandular partial submuscular or completely submuscular position, with the implant being inserted, or removed, through the incision. Like the peri-areolar incision, the inframammary fold incision provides for all three placement types and both insertion and removal of the implant through the incision. The incision is made in the crease under the breast, allowing for discreet scarring. Once the incision is made, the implant is inserted and worked vertically into place.
The transaxillary incision is made in the armpit. The incision is made in the fold of the armpit and a channel is cut to the breast. The implant is inserted into the channel and worked into place. Like the peri-areolar and crease incisions, the armpit incision can be used for implant placement anywhere in the breast. If a complication occurs that requires revision or removal of the implant, the surgeon will likely have to make a peri-areolar or inframammary fold incision to revise the position of the implant. The transaxillary incision is rarely reused because it is difficult to work on an implant from what is really a remote site. Visibility inside the breast is extremely limited for the surgeon with a transaxillary incision without the use of a fiber optic endoscope, which can be cumbersome in a revisional setting. In the case of reconstructive procedures, the patient's prior mastectomy incision is often used.
Once the incision is created, the surgeon must cut a path through the tissue to the final destination of the implant. Once that path has been created, the tissue and/or muscle (depending on placement) must be separated to create a pocket for the implant. When deciding where to cut the pocket in the breast, the surgeon must predict what the breasts will look like when the implants are filled.
Presently, there are very few techniques to reliably maintain the position of implants placed as part of cosmetic or reconstructive surgical procedures. Implant malposition may be the result of several factors, including poor surgical technique, i.e. the implant pocket is too big or too low; implant weight; or lack of soft tissue support. In addition, in reconstructive patients cancer treatments, such as chemotherapy, weaken the soft tissue and surgery, in general, interrupts the natural anatomic plains of the soft tissue. These factors are more profound in patients who have lost massive amounts of weight. Such situations typically provide extremely poor soft tissue support and the inability of the usual support structures within the breast, such as the inframammary fold, to support the weight of the implant.
Patient studies have demonstrated an 8-12% incidence of implant malposition severe enough to incur removal of the implant within 5 years. Over time, implants can be displaced medially resulting in symmastia (as is seen in FIG. 1), laterally resulting in implant excursion into the axilla of the chest cavity, or inferiorly resulting in “bottoming out” (as is seen in FIG. 2).
Symmastia is commonly referred to as “bread loafing” and is commonly seen in patients who have subglandular implants. With this condition, the implant pockets actually meet in the middle of the chest, giving the appearance of one breast 2 (FIG. 1), instead of two. The condition is most often related to technical error by a surgeon attempting to create too much cleavage in the patient or using an overly wide implant. Lateral displacement results in the implant moving into the armpit, especially when the patient is lying flat on her back. Lateral displacement is most common with submuscular placement when muscle is inadequately released medially and is the most under-recognized implant displacement problem.
Inferior displacement or “bottoming out” is described as a lengthening of the distance from the nipple to inframammary fold. This type of displacement results from a lowering of the inframammary fold during surgery or an inadequacy of soft tissue support required to maintain the implant weight. FIG. 2 shows a breast implant 4 that has bottomed out after sub-muscular placement within the patient. FIG. 2 also shows the proper location of an implant 6 that has not bottomed out. Bottoming out of implants may be exacerbated by a failure to wear a bra, activities resulting in excessive “bouncing” of the implants, excessively large implants, and/or extreme weight loss. Once these problems are established, classical repair techniques have had limited effectiveness, with high rates of displacement recurrence.
The traditional method of correction for implant malposition has utilized the scar tissue “capsule” as the strength of the repair. In most descriptions, the capsule is allowed several months to “mature” at which point the patient is taken to surgery, a section of the scar capsule excised or imbricated on itself and the remaining capsule closed using non-resorbable sutures.
The problems with this method are numerous. First, the scar capsule is often attenuated making adequate “bites” of capsule impossible. Second, the capsule is itself distensible so the factors which initially acted on the pocket can result in rapid recurrence. Finally, and most obviously, in nearly all cases the implant is replaced once the repair is complete—once again putting strain on the repair especially in the case of bottoming out. Some authors have advocated the use of percutaneous bolsters 8 (seen in FIGS. 3 and 4) placed to buttress the repair and take pressure off the internal repair. These bolsters may limit direct implant pressure but leave unattractive scars on the skin due to the tension. For medial malposition, the use of a Thongbra® (a bra designed to apply pressure over the sternum) or bolsters placed to secure the medial breast skin to the underlying sternum have had limited success.